Spaceflight outside of the Earth's protective magnetic field is dangerous from a cosmic radiation perspective. Inside Earth's magnetic field, where the manned International Space Station (ISS) orbits, the radiation encountered is minimal and almost all is deflected by our planet's magnetic fields. However, outside that protective shield, the Sun's solar wind (high energy radiation, solar energetic particles or SEPs) consisting of protons, electrons, alpha particles and plasmas continuously bombards the spacecraft for the months or years of spaceflight. On occasion the Sun produces a CME (Coronal Mass Ejection) that vastly increases the energy and volume of this radiation. These particles damage human DNA as well as living tissue and can destroy sensitive electronics.
The typical remedy has been to harden the electronics and software from these high-speed particles and placing heavy shielding in these manned or sensitive areas. This adds for considerable weight (and cost) to the launch vehicle, reducing needed payload, and is passive in nature.
These SEPs and CMEs can be deflected by a magnetic field as known by those skilled in the art to pass around the spacecraft and not be absorbed by it. This deflection of solar wind and radiation is well understood to be due to the Lorentz force. However, a magnetic field that is attached to the spacecraft (as seen in prior art) and enclosing it would cause other shielding issues with equipment and would require much more electrical power to operate (due to the need to enclose the entire spacecraft within that attached magnetic field), not to mention that it would perturb the data collection and transmissions of the spacecraft. In addition, much like the Van Allen radiation belt around the Earth, the generated magnetic field can capture some of this solar radiation as a plasma within the magnetic torus further impeding scientific data collection with its close position to the spacecraft.